Sound absorbers have been widely used in a number of different applications for absorbing sound. Known sound absorbers include, for example, fiber-based sound absorbers (for example, sound absorbers comprising fiberglass, open-cell polymeric foams, or fibrous materials) and perforated sheets. Microperforated films, for example, can function in the medium to high frequency absorption ranges with relatively good performance in the 800 Hz range and up.
Most sound absorbers, however, do not handle transmission loss well. Relatively low frequency transmission loss is therefore typically controlled using lots of mass (for example, steel plates, lead, concrete, or gypsum board).